OO gauge GWR Mogul and Prairie

[Miss Prism]

12 minutes ago, coeurdelyon said:

I am attaching herewith the picture we used for the livery of 5190 taken from Great Western Railway Journal to satisfy all concerned

 

Thanks, Richard, I should have known about that one!

 

[Harlequin]

33 minutes ago, melmerby said:

Interersting mod.

R3 & R4 appear to be the pull down resistors.

Any idea what value they are?

 

I was wondering whether reducing those rather than changing the leds would be of any benefit?

 

They are 1k. It would be an interesting experiment to change them but they are absolutely tiny and I think the position of Dapol's LEDs is a big part of the problem so making them brighter might not help.

 

BTW: Kudos to Dapol for providing complete wiring diagrams in the manuals. They made it much easier to understand how the circuits worked and how to modify them.

 

[melmerby]

1 hour ago, Harlequin said:

 

They are 1k. It would be an interesting experiment to change them but they are absolutely tiny and I think the position of Dapol's LEDs is a big part of the problem so making them brighter might not help.

 

BTW: Kudos to Dapol for providing complete wiring diagrams in the manuals. They made it much easier to understand how the circuits worked and how to modify them.

 

Thanks, I'm not averse to changing SMDs*, having just moved a similar sized one from one Arduino Nano to another.

I shall have to look in my Mogul manual, I must admit I hadn't noticed the wiring diagram.

 

* as long as they aren't stuck down as well as being soldered, which occasionally they are.

[melmerby]

4 hours ago, Harlequin said:

 

BTW: Kudos to Dapol for providing complete wiring diagrams in the manuals. They made it much easier to understand how the circuits worked and how to modify them.

 

Unfortunately not in the Mogul manual.

Dapol also do not routinely put manuals on their website, unlike Hornby.

 

Any chance of posting a copy?

 

[Harlequin]

3 hours ago, melmerby said:

Unfortunately not in the Mogul manual.

Dapol also do not routinely put manuals on their website, unlike Hornby.

 

Any chance of posting a copy?

 

It's probably copyright so I've sent you a PM.

 

[Hilux5972]

So I have finally got around to making some adjustments to the totally dull, almost invisible firebox flicker on my Prairie. I moved the LED panel to face outwards from the firebox instead of upwards. It took a little bit of trial and error to get them in the correct place, which is roughly about 1/3 to 1/2 of the way down the vertical section directly behind the cab backhead. It was superglued in place as the electrical tape just wouldn’t stick to the chassis in that area. I forgot to take a photo of the position before reassembling, but the 2nd photo shows them facing directly out from the firebox. Lights up the cab nicely now. May not be very prototypical but I like it. One of Dapol Imperium decoders has the flicker on Function 1 but for any other decoder it’s on Function 0.  

Edited February 9, 2022 by Hilux5972
Added content

[57xx]

Has anyone seen/heard any further news of the 43xx Mogul releases? The latest I can see on the Dapol site is the product release page still showing CADs and models "available Q1 – Q2 2022", and the pre-order page again just showing CADs and all for DCC sound fitted locos, nothing else.

[Hilux5972]

23 hours ago, 57xx said:

Has anyone seen/heard any further news of the 43xx Mogul releases? The latest I can see on the Dapol site is the product release page still showing CADs and models "available Q1 – Q2 2022", and the pre-order page again just showing CADs and all for DCC sound fitted locos, nothing else.

Was there more to be released? They were  released long before the Prairie. Have they announced another run?

[57xx]

3 minutes ago, Hilux5972 said:

Was there more to be released? They were  released long before the Prairie. Have they announced another run?

 

Yes, the first run was the later 63xx variant, they announced a run of the original 43xx variant early last year, it is slated to have fixed issues like gearing and slide bars.

 

https://www.Dapol.co.uk/New-OO-Gauge-43xx-2-6-0-Mogul

 

I've found some DC ones on Hattons, but most vendors are mislabelling the 63xx as 43xx so it's hard to find who is doing which version.

Edited February 15, 2022 by 57xx

[melmerby]

6 hours ago, 57xx said:

 

Yes, the first run was the later 63xx variant, they announced a run of the original 43xx variant early last year, it is slated to have fixed issues like gearing and slide bars.

 

 

I thought the Praries were supposed to have these "improvements" but in the end didn't.

 

The slide bars need a re-design of the motion and if it is absolutely true to scale it won't work.

Hornby got around this by having the connecting rod just behind the slide bars, it looks OK and obviates the need for the turned up ends

The prototype's slide bars have a chamfered cut out at the end to allow for the "clash" of the connecting rod and slide bar at top and bottom of the stroke.

[Chuffer Davies]

25 minutes ago, melmerby said:

 

The prototype's slide bars have a chamfered cut out at the end to allow for the "clash" of the connecting rod and slide bar at top and bottom of the stroke.

The centre line of the slide bars is 2.5 inches above that of the driving wheels and because of this it is only the bottom slide bar that requires the chamfered slot to clear the connecting rod.  This can be reproduced in model form, I know because I’ve done it, but only on a model designed to go around 3ft  radius (or greater) curves.  Dapol need not have splayed the top slide bar therefore.  
Frank

[1466]

7 hours ago, melmerby said:

I thought the Praries were supposed to have these "improvements" but in the end didn't.

 

The slide bars need a re-design of the motion and if it is absolutely true to scale it won't work.

Hornby got around this by having the connecting rod just behind the slide bars, it looks OK and obviates the need for the turned up ends

The prototype's slide bars have a chamfered cut out at the end to allow for the "clash" of the connecting rod and slide bar at top and bottom of the stroke.

Has the gearing of 18:1 been changed on the Prarie ?

[57xx]

20 hours ago, melmerby said:

I thought the Praries were supposed to have these "improvements" but in the end didn't.

 

Yes, hence why I said slated to. I can't say I'm holding out much hope for them to have fixed it. IIRC the Prairie EP slidebars were straight, but not production ones, just like the first Moguls.

[Les1952]

23 hours ago, Chuffer Davies said:

The centre line of the slide bars is 2.5 inches above that of the driving wheels and because of this it is only the bottom slide bar that requires the chamfered slot to clear the connecting rod.  This can be reproduced in model form, I know because I’ve done it, but only on a model designed to go around 3ft  radius (or greater) curves.  Dapol need not have splayed the top slide bar therefore.  
Frank

 

Does that mean that if they didn't splay the top slide bar their model wouldn't go round curves of less than tree feet radius?   Not quite clear...

 

Les

 

[Chuffer Davies]

10 hours ago, Les1952 said:

 

Does that mean that if they didn't splay the top slide bar their model wouldn't go round curves of less than tree feet radius?   Not quite clear...

 

Les

 

Hi Les,

Splaying the slidebars has no effect on what radius curves the Dapol model will do around.  I was referring to my scratch built chassis where I included the milled slot in the bottom slidebar to clear the connecting rod instead of splaying the slidebar.  The tolerances are tight and so my model only has around 0.2mm play either side of the centre axle to ensure the connecting rods fall into the slidebar’s slot so my model won’t go round less than a 3ft radius curve.  
Hope that makes sense?

Frank 

[melmerby]

3 hours ago, Chuffer Davies said:

Hi Les,

Splaying the slidebars has no effect on what radius curves the Dapol model will do around.  I was referring to my scratch built chassis where I included the milled slot in the bottom slidebar to clear the connecting rod instead of splaying the slidebar.  The tolerances are tight and so my model only has around 0.2mm play either side of the centre axle to ensure the connecting rods fall into the slidebar’s slot so my model won’t go round less than a 3ft radius curve.  
Hope that makes sense?

Frank 

The problem with the models is the slide bars are way too thin, being similar thickness to the connecting rods, all due to modelling 00 gauge for tight radius curves.

I've got a Comet chassis, with much less side play than RTR, under a Mainline body and I still had to chamfer both top and bottom slide bar ends, although no where near as much as Dapol have splayed theirs.

As I've mentioned before, Hornby got around the problem by having the connecting rod just behind the slide bars. Although no prototypical, It looks so much better.

 

[sjrixon]

This loco is driving me crazy! I tweaked the pony truck, it's better, but it's still sticky. Slows to a halt and looses power almost everytime.

[outatime]

You could also modify the sprung middle axle and make sure the pickups are touching the wheels properly.

https://www.rmweb.co.uk/community/index.php?/topic/129125-oo-gauge-gwr-mogul-and-prairie/&do=findComment&comment=4663572

 

[Hilux5972]

1 hour ago, sjrixon said:

This loco is driving me crazy! I tweaked the pony truck, it's better, but it's still sticky. Slows to a halt and looses power almost everytime.

Mine was doing the same thing. I removed the rear pony truck to at least run it while I inspected the truck and it didn’t stop once. It will only take a round file to remove a few mm from the axle aperture to enable it to run properly I think. 

[Chuffer Davies]

1 hour ago, sjrixon said:

This loco is driving me crazy! I tweaked the pony truck, it's better, but it's still sticky. Slows to a halt and looses power almost everytime.

When you say that it slows to a halt do you mean it loses grip yet the wheels are still spinning, or do you mean it loses electrical continuity and comes to a complete stop?

[sjrixon]

Electrical continuity...

 

I think I need to take the pony truck off again! 

[boxbrownie]

Or you could send it back for a warranty repair, Dapol will never get the message otherwise.

[rembrow]

17 hours ago, sjrixon said:

Electrical continuity...

 

I think I need to take the pony truck off again! 

If it runs ok without the rear pony truck, then it's not electrical, as there are no pickups in the pony truck. If it continues, it's likely to be because the pony truck is too rigid, and causes the chassis to lift when it gets to raised sections on points. The truck is meant to have compensation, as the wheels are sprung, however when on the flat, the amount of upward movement is fully used, and the truck becomes rigid. The solution seems to be to lengthen the existing slots in the pony truck, by a couple of mm, to enable the wheelset to have upward movement, which will allow it to move over raised sections, without lifting the driving wheels. Have done this modification on my two and it's been successful.

Edited February 21, 2022 by rembrow
Correction

[PJT]

17 hours ago, sjrixon said:

Electrical continuity...

 

I think I need to take the pony truck off again! 

 

2 hours ago, rembrow said:

If it runs ok without the pony truck, then it's not electrical, as there are no pickups in the pony truck.

 

I don't have a Dapol Prairie but I do have two Dapol GWR Moguls, both of which have suffered from the same electrical issue on the pony truck, despite it not having pick ups.  I would think that construction of the Prairie front pony is probably the same as that on the Mogul, so your issue might just be the same as the one I had.

 

Both my Moguls had an intermittent electrical shorting problem that, after several close inspections of the chassis, was driving me nuts since the locos were very poor, stuttering runners, especially on curves and points.  Then I discovered the front pony axle is a two piece item - two half axles, each carrying a non-insulated wheel, that almost but not quite touched each other in the middle of the pony truck.  Except, unfortunately, mine were so close to each other that on curves and points (and on occasion on straights as well) they did come into contact with each other, causing a momentary short circuit, hence the stuttering running.  

 

A tiny disc of very thin plastkard on the end of one half axle cured the issue and instantly both locos ran as beautifully as I'd hoped for.  I suppose a tiny dot of paint or similar would work too.

 

Incidentally, both locos were prone to the odd derailment, and it was after measuring the back to back of the front pony wheels and finding they were too close together that I stumbled across the non-insulated axles touching each other.

 

Hope that helps sort out your frustrating problems.

 

Pete T.

 

 

[rembrow]

53 minutes ago, PJT said:

 

 

I don't have a Dapol Prairie but I do have two Dapol GWR Moguls, both of which have suffered from the same electrical issue on the pony truck, despite it not having pick ups.  I would think that construction of the Prairie front pony is probably the same as that on the Mogul, so your issue might just be the same as the one I had.

 

Both my Moguls had an intermittent electrical shorting problem that, after several close inspections of the chassis, was driving me nuts since the locos were very poor, stuttering runners, especially on curves and points.  Then I discovered the front pony axle is a two piece item - two half axles, each carrying a non-insulated wheel, that almost but not quite touched each other in the middle of the pony truck.  Except, unfortunately, mine were so close to each other that on curves and points (and on occasion on straights as well) they did come into contact with each other, causing a momentary short circuit, hence the stuttering running.  

 

A tiny disc of very thin plastkard on the end of one half axle cured the issue and instantly both locos ran as beautifully as I'd hoped for.  I suppose a tiny dot of paint or similar would work too.

 

Incidentally, both locos were prone to the odd derailment, and it was after measuring the back to back of the front pony wheels and finding they were too close together that I stumbled across the non-insulated axles touching each other.

 

Hope that helps sort out your frustrating problems.

 

Pete T.

 

 

With the Prairie, it's the rear pony truck that is the problem, as when the loco is on the level, the truck and wheelset are unable to move upwards, thus creating a long fixed wheelbase. The rear pony has slots and springs on each side, intended to give upward movement, but it doesn't work, as the slot is not long enough and the wheelset is fully in the slot when on the level. Hopefully Dapol will make a modification on future runs, to increase the slot length.